Early oncofetal antigenic modifications during rat colonic carcinogenesis.

M1 antigens, associated with adult rat surface gastric epithelium and which are present in fetal but not adult distal colon, were investigated in this colonic mucosa during carcinogenesis. Fifty Wistar rats were given s.c. injections of 1,2-dimethylhydrazine for 28 weeks. Using an immunohistochemical method, M1 antigens associated with goblet cells were shown to be present after 2 weeks of 1,2-dimethylhydrazine treatment in histologically normal mucosa and then in 78% of mucinous hyperplasia and polypoid-like glands, in 54% of hyposecreting glands, in 58% of dysplasias, Grades 1 and 2, in two of 12 dysplasias, Grade 3, and in five of five transitional mucosas adjacent to carcinoma. The production of sialomucins associated with M1 antigens was often seen in the same histological lesion, although not always associated in the same goblet cells. The number of these histological lesions as well as the production of M1 antigens increased with the number of injections. Thus, these antigenic changes of an oncofetal nature can be regarded as early transformations of goblet cell differentiation in colonic mucosa subjected to chemical carcinogen.